fs/btrfs/acl.c

   1 /*
   2  * Copyright (C) 2007 Red Hat.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/string.h>
  21 #include <linux/xattr.h>
  22 #include <linux/posix_acl_xattr.h>
  23 #include <linux/posix_acl.h>
  24 #include <linux/sched.h>
  25
  26 #include "ctree.h"
  27 #include "btrfs_inode.h"
  28 #include "xattr.h"
  29
  30 #ifdef CONFIG_FS_POSIX_ACL
  31
  32 static void btrfs_update_cached_acl(struct inode *inode,
  33                                     struct posix_acl **p_acl,
  34                                     struct posix_acl *acl)
  35 {
  36         spin_lock(&inode->i_lock);
  37         if (*p_acl && *p_acl != BTRFS_ACL_NOT_CACHED)
  38                 posix_acl_release(*p_acl);
  39         *p_acl = posix_acl_dup(acl);
  40         spin_unlock(&inode->i_lock);
  41 }
  42
  43 static struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  44 {
  45         int size;
  46         const char *name;
  47         char *value = NULL;
  48         struct posix_acl *acl = NULL, **p_acl;
  49
  50         switch (type) {
  51         case ACL_TYPE_ACCESS:
  52                 name = POSIX_ACL_XATTR_ACCESS;
  53                 p_acl = &BTRFS_I(inode)->i_acl;
  54                 break;
  55         case ACL_TYPE_DEFAULT:
  56                 name = POSIX_ACL_XATTR_DEFAULT;
  57                 p_acl = &BTRFS_I(inode)->i_default_acl;
  58                 break;
  59         default:
  60                 return ERR_PTR(-EINVAL);
  61         }
  62
  63         spin_lock(&inode->i_lock);
  64         if (*p_acl != BTRFS_ACL_NOT_CACHED)
  65                 acl = posix_acl_dup(*p_acl);
  66         spin_unlock(&inode->i_lock);
  67
  68         if (acl)
  69                 return acl;
  70
  71
  72         size = __btrfs_getxattr(inode, name, "", 0);
  73         if (size > 0) {
  74                 value = kzalloc(size, GFP_NOFS);
  75                 if (!value)
  76                         return ERR_PTR(-ENOMEM);
  77                 size = __btrfs_getxattr(inode, name, value, size);
  78                 if (size > 0) {
  79                         acl = posix_acl_from_xattr(value, size);
  80                         btrfs_update_cached_acl(inode, p_acl, acl);
  81                 }
  82                 kfree(value);
  83         } else if (size == -ENOENT) {
  84                 acl = NULL;
  85                 btrfs_update_cached_acl(inode, p_acl, acl);
  86         }
  87
  88         return acl;
  89 }
  90
  91 static int btrfs_xattr_get_acl(struct inode *inode, int type,
  92                                void *value, size_t size)
  93 {
  94         struct posix_acl *acl;
  95         int ret = 0;
  96
  97         acl = btrfs_get_acl(inode, type);
  98
  99         if (IS_ERR(acl))
 100                 return PTR_ERR(acl);
 101         if (acl == NULL)
 102                 return -ENODATA;
 103         ret = posix_acl_to_xattr(acl, value, size);
 104         posix_acl_release(acl);
 105
 106         return ret;
 107 }
 108
 109 /*
 110  * Needs to be called with fs_mutex held
 111  */
 112 static int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 113 {
 114         int ret, size = 0;
 115         const char *name;
 116         struct posix_acl **p_acl;
 117         char *value = NULL;
 118         mode_t mode;
 119
 120         if (acl) {
 121                 ret = posix_acl_valid(acl);
 122                 if (ret < 0)
 123                         return ret;
 124                 ret = 0;
 125         }
 126
 127         switch (type) {
 128         case ACL_TYPE_ACCESS:
 129                 mode = inode->i_mode;
 130                 ret = posix_acl_equiv_mode(acl, &mode);
 131                 if (ret < 0)
 132                         return ret;
 133                 ret = 0;
 134                 inode->i_mode = mode;
 135                 name = POSIX_ACL_XATTR_ACCESS;
 136                 p_acl = &BTRFS_I(inode)->i_acl;
 137                 break;
 138         case ACL_TYPE_DEFAULT:
 139                 if (!S_ISDIR(inode->i_mode))
 140                         return acl ? -EINVAL : 0;
 141                 name = POSIX_ACL_XATTR_DEFAULT;
 142                 p_acl = &BTRFS_I(inode)->i_default_acl;
 143                 break;
 144         default:
 145                 return -EINVAL;
 146         }
 147
 148         if (acl) {
 149                 size = posix_acl_xattr_size(acl->a_count);
 150                 value = kmalloc(size, GFP_NOFS);
 151                 if (!value) {
 152                         ret = -ENOMEM;
 153                         goto out;
 154                 }
 155
 156                 ret = posix_acl_to_xattr(acl, value, size);
 157                 if (ret < 0)
 158                         goto out;
 159         }
 160
 161         ret = __btrfs_setxattr(inode, name, value, size, 0);
 162
 163 out:
 164         kfree(value);
 165
 166         if (!ret)
 167                 btrfs_update_cached_acl(inode, p_acl, acl);
 168
 169         return ret;
 170 }
 171
 172 static int btrfs_xattr_set_acl(struct inode *inode, int type,
 173                                const void *value, size_t size)
 174 {
 175         int ret = 0;
 176         struct posix_acl *acl = NULL;
 177
 178         if (value) {
 179                 acl = posix_acl_from_xattr(value, size);
 180                 if (acl == NULL) {
 181                         value = NULL;
 182                         size = 0;
 183                 } else if (IS_ERR(acl)) {
 184                         return PTR_ERR(acl);
 185                 }
 186         }
 187
 188         ret = btrfs_set_acl(inode, acl, type);
 189
 190         posix_acl_release(acl);
 191
 192         return ret;
 193 }
 194
 195
 196 static int btrfs_xattr_acl_access_get(struct inode *inode, const char *name,
 197                                       void *value, size_t size)
 198 {
 199         return btrfs_xattr_get_acl(inode, ACL_TYPE_ACCESS, value, size);
 200 }
 201
 202 static int btrfs_xattr_acl_access_set(struct inode *inode, const char *name,
 203                                       const void *value, size_t size, int flags)
 204 {
 205         return btrfs_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 206 }
 207
 208 static int btrfs_xattr_acl_default_get(struct inode *inode, const char *name,
 209                                        void *value, size_t size)
 210 {
 211         return btrfs_xattr_get_acl(inode, ACL_TYPE_DEFAULT, value, size);
 212 }
 213
 214 static int btrfs_xattr_acl_default_set(struct inode *inode, const char *name,
 215                                const void *value, size_t size, int flags)
 216 {
 217         return btrfs_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 218 }
 219
 220 int btrfs_check_acl(struct inode *inode, int mask)
 221 {
 222         struct posix_acl *acl;
 223         int error = -EAGAIN;
 224
 225         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 226
 227         if (IS_ERR(acl))
 228                 return PTR_ERR(acl);
 229         if (acl) {
 230                 error = posix_acl_permission(inode, acl, mask);
 231                 posix_acl_release(acl);
 232         }
 233
 234         return error;
 235 }
 236
 237 /*
 238  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 239  * stuff has been fixed to work with that.  If the locking stuff changes, we
 240  * need to re-evaluate the acl locking stuff.
 241  */
 242 int btrfs_init_acl(struct inode *inode, struct inode *dir)
 243 {
 244         struct posix_acl *acl = NULL;
 245         int ret = 0;
 246
 247         /* this happens with subvols */
 248         if (!dir)
 249                 return 0;
 250
 251         if (!S_ISLNK(inode->i_mode)) {
 252                 if (IS_POSIXACL(dir)) {
 253                         acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
 254                         if (IS_ERR(acl))
 255                                 return PTR_ERR(acl);
 256                 }
 257
 258                 if (!acl)
 259                         inode->i_mode &= ~current->fs->umask;
 260         }
 261
 262         if (IS_POSIXACL(dir) && acl) {
 263                 struct posix_acl *clone;
 264                 mode_t mode;
 265
 266                 if (S_ISDIR(inode->i_mode)) {
 267                         ret = btrfs_set_acl(inode, acl, ACL_TYPE_DEFAULT);
 268                         if (ret)
 269                                 goto failed;
 270                 }
 271                 clone = posix_acl_clone(acl, GFP_NOFS);
 272                 ret = -ENOMEM;
 273                 if (!clone)
 274                         goto failed;
 275
 276                 mode = inode->i_mode;
 277                 ret = posix_acl_create_masq(clone, &mode);
 278                 if (ret >= 0) {
 279                         inode->i_mode = mode;
 280                         if (ret > 0) {
 281                                 /* we need an acl */
 282                                 ret = btrfs_set_acl(inode, clone,
 283                                                     ACL_TYPE_ACCESS);
 284                         }
 285                 }
 286         }
 287 failed:
 288         posix_acl_release(acl);
 289
 290         return ret;
 291 }
 292
 293 int btrfs_acl_chmod(struct inode *inode)
 294 {
 295         struct posix_acl *acl, *clone;
 296         int ret = 0;
 297
 298         if (S_ISLNK(inode->i_mode))
 299                 return -EOPNOTSUPP;
 300
 301         if (!IS_POSIXACL(inode))
 302                 return 0;
 303
 304         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 305         if (IS_ERR(acl) || !acl)
 306                 return PTR_ERR(acl);
 307
 308         clone = posix_acl_clone(acl, GFP_KERNEL);
 309         posix_acl_release(acl);
 310         if (!clone)
 311                 return -ENOMEM;
 312
 313         ret = posix_acl_chmod_masq(clone, inode->i_mode);
 314         if (!ret)
 315                 ret = btrfs_set_acl(inode, clone, ACL_TYPE_ACCESS);
 316
 317         posix_acl_release(clone);
 318
 319         return ret;
 320 }
 321
 322 struct xattr_handler btrfs_xattr_acl_default_handler = {
 323         .prefix = POSIX_ACL_XATTR_DEFAULT,
 324         .get    = btrfs_xattr_acl_default_get,
 325         .set    = btrfs_xattr_acl_default_set,
 326 };
 327
 328 struct xattr_handler btrfs_xattr_acl_access_handler = {
 329         .prefix = POSIX_ACL_XATTR_ACCESS,
 330         .get    = btrfs_xattr_acl_access_get,
 331         .set    = btrfs_xattr_acl_access_set,
 332 };
 333
 334 #else /* CONFIG_FS_POSIX_ACL */
 335
 336 int btrfs_acl_chmod(struct inode *inode)
 337 {
 338         return 0;
 339 }
 340
 341 int btrfs_init_acl(struct inode *inode, struct inode *dir)
 342 {
 343         return 0;
 344 }
 345
 346 int btrfs_check_acl(struct inode *inode, int mask)
 347 {
 348         return 0;
 349 }
 350
 351 #endif /* CONFIG_FS_POSIX_ACL */